Presenter of papers on the Egyptian Taste at The Inspiration of Egypt exhibition at Brighton Royal Pavilion and Manchester Art Galleries in 1982

Presenter of major paper on the architecture and landscapes of death at the international conference on funerary art and architecture in Seville, 1991. Contributor to the Seville Declaration on the future conservation policies of cemeteries in Europe and the Americas

Contributor to several major symposia and conferences, including Society of Antiquaries of London, European Architectural Heritage Year, the Bologna Conference on ‘Egypt outside Egypt’, the Andalucian Conference on monumental architecture, the Cambridge Summer School, and many other venues

Contributor to the University of Cambridge Board of Extra-Mural Studies International Summer Schools, 1991 

Contributor to the University of Cambridge Board of Extra-Mural Studies International Summer Schools, 1992 

Contributor to the University of Cambridge Board of Extra-Mural Studies International Summer Schools, 1993

Contributor to International Symposium ‘A Republic for the Ages’ under the aegis of the United States Capitol Historical Society, Washington D C, March 1993

Contributor to International Symposium on Aspects of Death in Art entitled 0 Triunfo de Thanatos: a arte e a morte at the University of Coimbra, Portugal, September 1993

Contributor to International Symposium on the Ancient Egyptian influence on Western Art and Architecture at The Louvre, Paris, April 1994. Later published in L’Egyptomanie a l’épreuve de l’ archéologie

Contributor to a film on the Life and Work of Alexander ‘Greek’ Thomson as part of a major International Exhibition held in 1999

Contributor to Symposium on Monumental Architecture, Antwerp, 1999

Keynote paper on the Architecture of transplanted cultures at the Annual Conference of the Society for the Study of Architecture in Canada at Halifax, Nova Scotia, 1999

Paper on the Londonderry Plantation given at Concordia University, Montréal, Canada, 1999

Paper on Elegiac Gardens and the Enlightenment at the Canonbury Centre for Masonic Studies 1999

Paper on the Londonderry Plantation given at the North Coast branch of the National Trust, Coleraine, April 2000

Esdaile Memorial Lecture given at Stamford, Lincolnshire, in March 2002

Paper on Edward Young and the Garden Cemetery Movement given in London in May 2002

Paper on Egyptomania given at the Canonbury Masonic Research Centre, London, in June 2002

Paper on Freemasonry and Garden Design given to the Quatuor Coronati Reseach Lodge, Freemasons’ Hall, London, 2003

Paper on Ninian Comper and the Late Gothic Revival given at St Cyprian’s, Clarence Gate, London, October 2003

Paper on The Grocers’ Company Estates in Co Londonderry given at Grocers’ Hall, London, February 2004

Paper on ‘The Egyptian Revival’ given to the Ulster Architectural Heritage Society, March 2004

Allison Memorial Lecture on ‘The Late Gothic Revival: a Corrective View’ given at the Museum, New Walk, Leicester, December 2004

Keynote lecture on Symbolism in Gardens: An Introduction given at an International Symposium on Symbolism in 18th-Century Gardens held at the Schloss at Schwetzingen, Germany, 28-29 September 2006

Lecture on ‘Death and Architecture: Salubrious Dwellings for the Dead’ to  launch The Follies Trust in Bedford Hall, Dublin Castle, 7 November 2006

Lecture on ‘Freemasonry and the Enlightenment’ in the Douglas Knoop Centre at Sheffield University,  5 December 2006

Keynote lecture at Rewley House, University of Oxford, as part of a one-day Symposium to celebrate the thirtieth anniversary of the publication of The Erosion of Oxford, 3 February 2007

Lecture on the ‘Origins of the Garden Cemetery’ at the University of Southampton, 13 March 2007

Lecture on ‘Death and Architecture’ in Knockbreda Parish Church, County Down, 20 March 2007

Lecture (27 May 2007) on ‘Freemasonry and Garden History: Ideas, Allusions, Fabriques, and the Enlightenment’, as part of the International Conference on the History of Freemasonry held at Freemasons’ Hall, George Street, Edinburgh, 25-27 May 2007

Lecture on The Egyptian Revival given to the Anglo-Egyptian Society, University of London, 27 September 2007

Lecture on Garden-Design and the Enlightenment given to the Ulster Architectural Heritage Society at Clifton House, Belfast, 12 March 2008

Lecture on The Egyptian Revival at The Sunday Times Oxford Literary Festival at Christ Church Oxford, 5 April 2008

Keynote lecture on ‘The Londonderry Plantation: Reluctant Colonisers’ at the conference entitled Across the Narrow Sea held in Monaghan, Republic of Ireland, 7 November 2008

Keynote lecture on ‘Imagery associated with Mozart's Masonic works: stage-sets and their sources’ at the two-day conference entitled The Expression of Freemasonry in The International School of The Hague, Netherlands, 27-28 November 2008

Panel member at Symposium on Mozart’s Magic Flute at the University of Sheffield, 16-17 February 2009

Lecture on ‘The Egyptian Revival’ at the University of York, 11 June 2009

Keynote lecture on ‘Reluctant Colonisers’ at Goldsmiths' College London, as part of the International Conference, The Plantation of Ulster 1609-2009: A Laboratory for Empire, 25-26 June 2009

‘Salubrious Dwellings for the Dead’:  paper on Mausolea at the University of Gent, Belgium, 23 October 2009

‘The Landscape Garden and Freemasonry’: paper delivered at the Institute for Garden and Landscape History, University of Bristol, 25 June 2011